It's done, it worked, and it sounds great! [Archive] - Audio & Video Forums

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emaidel
02-05-2009, 05:14 AM
I recently posted the fact that the upper bass driver in one of my Dahlquist DQ-10's was failing, and that I was faced with paying Regnar of NY a lot to rebuild both, which is recommended, or purchasing two new, and very different drivers from Parts EXpress. I was incorrect regarding Regnar's pricing for the rebuild of these 5" drivers: their price isn't $150 each, but "only" $90 each. The new, Dayton Audio drivers from Parts Express were only $22 and change each.

The Dayton drivers are, from outward appearances, infinitely superior drivers in and of themselves. Instead of a relatively cheap, stamped basket, they're housed in cast aluminum baskets, with a magnet of substantially more weight. The cone material is a black shiny substance (common to many a driver today) with a butyl rubber surround. Installation wasn't exactly "a breeze" since the mounting holes on the masonite panel in the DQ-10's and those on the Dayton Audio drivers don't line up, but there are certainly more difficult challenges to overcome.

Once I installed one, I decided to listen to the speaker before I replaced the other. Everything sounded just fine, and even a bit clearer in areas I wouldn't have expected, notably in upper midrange. Why this should be so is something I can't explain. So, I then replaced the upper bass driver in the other speaker. I also replaced a dead piezo supertweeter in one speaker with the incredibly cheap ($1.44 each!) unit I bought from Parts Express, and can't detect any difference whatsoever between it and the original. Both are really cheap products, weighing about a half a pound each (if that much!), yet, with so little coming from them, being crossed over at 12,000HZ, I have to agree with Jon Dahlquist's decision to use such crappy drivers, as they work just fine in that regard, and don't offer the characteristically unpleasant stident top end response when used as a primary tweeter in lesser systems.

Then I sat down to listen, and to listen critically before I reassembled the grilles. I have to admit that, while all I had in mind was correcting a problem, I did indeed wind up upgrading my DQ-10's. On much material, there's little difference, but when playing a Telarc CD of Handel's "Messiah" performed by the Boston Baroque, I was all but knocked over at the increased clarity and detail in the human voice - especially tenors and basses. Samples of various Beethoven symphonies on the BIS/Vanska series also resulted in increased detail and a far more musical quality to French horns, trombones and woodwinds.

Unfortunately, the original problem still exists, though to a lesser degree. That suggests that the original driver may not have been defective to begin with, but that something (perhaps a capacitor?) in the crossover is failing. There's also the possibility that the new drivers need to burn in for a while, and loosen up some. That's certainly what I'm hoping is the case, and while listening to a few selections yesterday, I didn't hear any difficulties at all, so perhaps there isn't anything wrong with the crossover. Only time will tell, and if the problem persists, I'll have to give the folks at Regnar a call to discuss which component of the crossover is the likely culprit.

Still, replacing the upper bass drivers in a pair of DQ-10's with the Dayton Audio Reference 5" drivers, for less than $23 each, is a modest investment resulting in a disproportionate improvement. Most highly recommended!

Feanor
02-05-2009, 07:11 AM
....
Unfortunately, the original problem still exists, though to a lesser degree. That suggests that the original driver may not have been defective to begin with, but that something (perhaps a capacitor?) in the crossover is failing. There's also the possibility that the new drivers need to burn in for a while, and loosen up some. That's certainly what I'm hoping is the case, and while listening to a few selections yesterday, I didn't hear any difficulties at all, so perhaps there isn't anything wrong with the crossover. Only time will tell, and if the problem persists, I'll have to give the folks at Regnar a call to discuss which component of the crossover is the likely culprit.
...

I don't just recall what you original problem was, emaidel, except you said the mid-bass was failing. Would you remind us?

I would guess if anything was going to fail in crossover, it would be a never very good solder joint succuming to vibration or oxidation, or a capacitor -- inductors or resistors failures are almost unheard of.

In any case, lots of people maintain the crossover capacitor upgrades significantly improve sound quality.

spasticteapot
02-05-2009, 07:54 AM
Those Dayton woofers are not recommended for the 1st-order crossovers Dahlquist used - you're much better off with a Vifa poly cone or Seas paper cone. Metal-cone drivers are generally superior to their paper- and poly-coned counterparts until you hit a given frequency - say, 2.6khz - where everything simply goes to ringing resonance hell.

Also, I highly recommend the Dayton film caps for re-capping speakers. Well made, sold in a wide variety of sizes, and cheap. A 20% change in the value of any capacitor in the system could cause a drastic change in the sound, and old electrolytic caps are often even worse than that.

Feanor
02-05-2009, 08:40 AM
Those Dayton woofers are not recommended for the 1st-order crossovers Dahlquist used - you're much better off with a Vifa poly cone or Seas paper cone. Metal-cone drivers are generally superior to their paper- and poly-coned counterparts until you hit a given frequency - say, 2.6khz - where everything simply goes to ringing resonance hell.

Also, I highly recommend the Dayton film caps for re-capping speakers. Well made, sold in a wide variety of sizes, and cheap. A 20% change in the value of any capacitor in the system could cause a drastic change in the sound, and old electrolytic caps are often even worse than that.

'Teapot, you're totally right about metal cones having sharp resonances about their intented frequency ranges and the 1st order crossovers aren't usually sufficient to surpress these. And I forgot that the Dalquists used 1st order XOs.

I note that the PE Reference 5" has a pronouced resonance at about 7500 Hz and a really nasty one at around 12,000 Hz; see here (http://www.parts-express.com/pdf/295-360s.pdf). Whether a 1st order might work depends on the XO point. If the point is 3000 Hz response will be done only 7 dB or so (6 dB/octave) at 7500 Hz which is insufficient. If the point is 2000 Hz, it will be down 10-11 dB which might be barely sufficient.

Because the Dalquist is "time-aligned" it wouldn't work to just substitute a 2nd order XO, though a 3rd order might work, possibly with inverted polarity. Or possibly some sort of frequency band filter could be used.

emaidel
02-05-2009, 11:47 AM
The original problem was a crackling sound that seemed to be coming from the mid bass driver. I wasn't looking specifically for a replacement, and quite accidentally stumbled upon the Parts Express website where an individual specifically recommended the Dayton Audio 5 inchers as a replacement/upgrade.

Whether or not the Dayton woofers have a peak around 7,500 HZ is immaterial, given the very narrow range the upper bass drivers cover - 7,500HZ is way beyond that which comes out of this driver.

After listening a little more, and noticing the original problem still occurring, I realized, only after removing the grille and listening carefully to each driver, that the problem all along was in the woofer, and not the upper bass driver. The "crackling" sound, as it is of a much higher frequency than that which ordinarily is reproduced by the woofer, merely appeared to be coming from another location within the speaker, and as I had both woofers rebuilt about 3 years ago by Regnar, I assumed it was something other than the woofer.

I had a brief phone conversation with Joe at Regnar who said that if it's crackling that I'm hearing, then most likely, the woofer is blown. Unfortunately, the warranty for the rebuild is only one year, and my only alternative is to have the woofer rebuilt (unless I can find one elsewhere) for the current price of $175 (it used to cost $139.50).

In the meantime, as long as I don't play the system too loudly, and don't play material with very strong bass, it still sounds wonderful, and noticeably better than prior to installing the Dayton drivers. Whether or not they're "recommended," the system sounds terrific with them in place, and I'd recommend them to anyone, but thanks for the suggestions nonetheless.

Feanor
02-05-2009, 12:11 PM
The original problem was a crackling sound that seemed to be coming from the mid bass driver. I wasn't looking specifically for a replacement, and quite accidentally stumbled upon the Parts Express website where an individual specifically recommended the Dayton Audio 5 inchers as a replacement/upgrade.

Whether or not the Dayton woofers have a peak around 7,500 HZ is immaterial, given the very narrow range the upper bass drivers cover - 7,500HZ is way beyond that which comes out of this driver.

After listening a little more, and noticing the original problem still occurring, I realized, only after removing the grille and listening carefully to each driver, that the problem all along was in the woofer, and not the upper bass driver. The "crackling" sound, as it is of a much higher frequency than that which ordinarily is reproduced by the woofer, merely appeared to be coming from another location within the speaker, and as I had both woofers rebuilt about 3 years ago by Regnar, I assumed it was something other than the woofer.

I had a brief phone conversation with Joe at Regnar who said that if it's crackling that I'm hearing, then most likely, the woofer is blown. Unfortunately, the warranty for the rebuild is only one year, and my only alternative is to have the woofer rebuilt (unless I can find one elsewhere) for the current price of $175 (it used to cost $139.50).

In the meantime, as long as I don't play the system too loudly, and don't play material with very strong bass, it still sounds wonderful, and noticeably better than prior to installing the Dayton drivers. Whether or not they're "recommended," the system sounds terrific with them in place, and I'd recommend them to anyone, but thanks for the suggestions nonetheless.

The proof is in the listening, so if it sounds good, it is good.

Let us know what you decide to do about the woofer. Very likely close matches exist amoungst currently available drivers.

hydroman
02-06-2009, 10:18 AM
^werd.

i would have done the same PE solution as well. There is a cost/benefit ratio. At least for me!